In recent years, wireless local area networks (LANs) have become widespread, and wireless LAN compatible products (hereinafter also referred to as “wireless communication devices”) have increased accordingly. Since a possibility of a decrease in communication efficiency increases as wireless communication devices increase, there is a demand for an improvement in communication efficiency.
One reason for the decrease in the communication efficiency is packet collision in a wireless LAN. For example, in an autonomous distributed wireless LAN, there are cases in which a plurality of wireless communication devices with overlapping communication ranges transmit packets at the same timing, and in this case, packet collision is likely to occur, and the packets are unlikely to be received by wireless communication devices that are transmission destinations.
In this regard, in an autonomous distributed wireless LAN, a technique called carrier sense is employed in order to avoid packet collision. In carrier sense, a wireless communication device monitors a use situation of a wireless transmission path around itself for a predetermined period of time before transmitting a packet and determines whether or not the wireless transmission path is being used by another wireless communication device. In a case in which the wireless transmission path is determined to be being used, the wireless communication device suppresses packet transmission.
Here, in a case in which a wireless communication scheme is different, unfairness of packet transmission opportunities may occur between wireless communication devices having different wireless communication schemes. For example, in a case in which a communication range of one wireless communication device is narrower than a communication range of another wireless communication device, the one wireless communication device is more likely to determine that a wireless transmission path is being used through carrier sense than the other wireless communication device. Therefore, the transmission opportunities of the one wireless communication device are reduced as compared with the other wireless communication device.
On the other hand, an invention in which, in a wireless communication device using a normal wireless communication scheme and a proximity wireless communication scheme, in a case in which the proximity wireless communication scheme is used, the transmission power is set to a value lower than the transmission power in the normal wireless communication scheme, and sensitivity of the carrier sense is set to be lower than sensitivity in the normal wireless communication scheme is disclosed in Patent Literature 1. According to the invention disclosed in Patent Literature 1, in a case in which the proximity wireless communication scheme is used, it is possible to suppress a reduction in transmission opportunities as compared with the case in which the normal wireless communication scheme is used.